Add initial Copilot instructions #4990

Job	Run time
Go: tracing with legacy workflow (macos-latest, stable-v2.16.6)	3m 55s
Go: tracing with legacy workflow (ubuntu-latest, stable-v2.18.4)	1m 25s
Go: tracing with legacy workflow (ubuntu-latest, stable-v2.17.6)	1m 15s
Go: tracing with legacy workflow (ubuntu-latest, stable-v2.20.7)	1m 21s
Go: tracing with legacy workflow (macos-latest, stable-v2.17.6)	4m 17s
Go: tracing with legacy workflow (macos-latest, stable-v2.20.7)	3m 46s
Go: tracing with legacy workflow (macos-latest, stable-v2.19.4)	3m 20s
Go: tracing with legacy workflow (ubuntu-latest, stable-v2.19.4)	1m 32s
Go: tracing with legacy workflow (macos-latest, linked)	3m 43s
Go: tracing with legacy workflow (macos-latest, stable-v2.18.4)	3m 25s
Go: tracing with legacy workflow (macos-latest, default)	4m 6s
Go: tracing with legacy workflow (ubuntu-latest, default)	1m 12s
Go: tracing with legacy workflow (macos-latest, nightly-latest)	4m 39s
Go: tracing with legacy workflow (ubuntu-latest, stable-v2.16.6)	1m 21s
Go: tracing with legacy workflow (ubuntu-latest, linked)	1m 12s
Go: tracing with legacy workflow (ubuntu-latest, nightly-latest)	1m 9s
	41m 38s

Provide feedback